This invention relates generally to a cage for a roller bearing, a roller bearing with a cage of this kind, a set of rollers for a roller bearing with a cage of this kind and methods for the production of such roller bearings or sets of rollers.
More particularly, the bearing rollers can be needle rollers or cylindrical rollers and the corresponding roller bearings can be needle or cylindrical-roller bearings. The bearings or bearing cages may be those in which webs which hold the bearing rollers apart in the circumferential direction are provided between the individual bearing rollers. However, the bearings of particular interest are full-complement bearings, i.e. bearings or sets of rollers in which the bearing rollers are in direct contact with one another along generatrices. Such full-complement bearings or bearing rings are advantageous when the radial loads on the roller bearing are high, i.e. when high static and/or dynamic load ratings are required. In such a case, a cage with webs between the rollers requires approximately 1/4 of the pitch circle space between the bearing rollers and is therefore not available for the bearing rollers.
According to the prior art, the bearing rollers in full-complement roller bearings without webs between the bearing rollers can be held by lubricating grease or by individual mounting plugs between the rollers, or an assembly sleeve of cardboard or plastic can be used to retain the rollers during assembly. In all these cases, however, there is no security against the loss of rollers during or before assembly. Such arrangements are therefore not suitable for safety components such as vehicle steering systems.
A full-complement roller bearing with retention of the bearing rollers on the inside is known in practice. It has a one-piece welded sheet metal cage which prevents the bearing rollers from falling in the inward direction and which, after the assembly of the bearing, runs along loosely between the rollers on the inside of the latter. For reasons of assembly, a cage of this kind can only be employed with bearings that have a single fixed flange on the outer race. If the outer race is designed as a sleeve which is appropriately thin radially, a second bearing flange can be formed, after the assembly of the cage with the bearing rollers, by bending the sleeve over the axial end of the cage. The installation of the cage is thus complex, and there is virtually no possibility of guidance for the cage on the bearing flanges. Moreover, in the case of bearings under high loads or with high load ratings, the outer bearing race or the outer bearing sleeve, or even the bearing cage, can break.
In the case of thick-walled bearing sleeves, there is the risk, when bending over the case-hardened and subsequently soft-annealed edges, that cracks will appear in the bent-over bearing flanges at the bending radius due to the carburization. There is furthermore the possibility that, during the annealing of the bent-over edges, the track will be tempered at the transition and will become soft.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
An object on which the invention is based is to facilitate the assembly of the bearing cage or of the set of rollers and its fitting on the roller bearing and, for example, to allow the bearing cage to be used also for roller bearings with two fixed flanges on the outer race or inner race. At the same time, the intention is also to allow the use of the cage, in particular in the form of a set of rollers, as a unit between two bearing tracks, and to exclude the possibility that the bearing will jam if the bearing cage breaks. The bearing should also be suitable particularly for high bearing pressures at low speeds e.g. for steering gears of vehicles.